Simplify the following expression: $k = \dfrac{5q}{10r + 30p} - \dfrac{5q - 5r}{10r + 30p}$ You can assume $p,q,r \neq 0$.
Explanation: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{5q - (5q - 5r)}{10r + 30p}$ $k = \dfrac{5r}{10r + 30p}$ The numerator and denominator have a common factor of $5$, so we can simplify $k = \dfrac{r}{2r + 6p}$